Apple's new iPhone 3.0 software is filled with more than 100 new features that make it a must-have update for any iPhone or iPod Touch user (even though iPod Touch users will need to shell out $9.95 for it while all iPhone users can get it for free). Once you've updated your iPhone or iPod Touch, here's your guide to the biggest and best new features and how to get make the most out of them.

Text Selection and Cut/Copy/Paste

One of the biggest new features of the iPhone is the ability to select and cut/copy and paste textsomething that iPhone owners have begged Apple to include since the first release nearly two years ago. For anyone who wants to copy information from a web page to an email or text message or into a form in a third-party app, this feature revolutionizes the way you use your iPhone. And it works across all apps that display text and use the iPhone keyboard for text entry (even copying photos is supported in many apps). And as this video from Apple’s website shows, using this feature is designed to be both easy and unobtrusive.

Undo

A similar feature to copy and paste in many Mac and Windows applications is the ability to undo your last action (typing, pasting, delete of text, etc.). iPhone OS 3 brings Undo to the iPhone in a way only Apple would think ofby shaking the phone itself. Shaking the phone while entering text of performing actions in supported apps will bring up a dialog asking if you want to undo your last action. Again, this makes the process easy to use, but it doesn’t add any buttons or menus that you need to access it. And because everyone makes typos (especially when using the iPhone’s onscreen keyboard), this is a really helpful addition.

Landscape Keyboard

Speaking of the keyboard, the iPhone now has broader support for using the keyboard in landscape mode. I’ve always championed the landscape keyboard, which was previously only available in Safari and some third-party apps, because it provides larger keys that are spaced further apart, making it easier to type on for many people without relying on the iPhone’s auto-correct feature. Apple now provides landscape mode in all the major built-in iPhone apps including Safari, Mail (which probably most needed it), Messages (the updates Text app), and Notes.

Spotlight

Apple has brought the Mac’s spotlight data indexing and search technology to the iPhone. The result is an addition to the home screen (technically an extra home screen devoted to search) that allows you to search for information across all the major iPhone applications. For example, if I put in the name John, I’ll see any notes about someone named John, all my emails from anyone named John (or that contain the name in the subject or text of the message), contacts for anyone named John, and calendar events that include the name as well. It also identifies apps that match a search stringwhich can make it a good app launcher if you’ve installed a lot of apps across multiple home screens and don’t want to scroll through looking for an app’s icon.

Spotlight is a live search, meaning that it begins displaying results as soon as you type them. This makes it a powerful time saver, and it means that you can easily find anything you need on your iPhone without needing to know exactly where it lives. After a few days of use, I actually find myself using Spotlight on my iPhone far more than I do on my Mac.

Another implementation of search on the iPhone is a universal search box in most major apps (Mail, Notes, Calendar, Messages, Contacts, and iPod). This live search box is like Spotlight for each application and allows you to search quickly and easily for specific emails, text messages, music, and such. The catch is that this box isn’t always visible; you’ll need to go to the top of the screen completely to see it bounce into view.

Push Notifications

Push notifications have been an elusive idea for the iPhone since last year’s Worldwide Developer’s Conference when Apple announced them. The idea is that they will allow your iPhone to receive updates for Internet-enabled apps (news viewers, instant messengers, social networking tools, etc.) even when the app isn’t running (Apple has said to maintain performance and stability so only one third-party app may run at a time). Notifications can display alerts (much like text messages), play a custom sound, or add a number badge to an app’s icon (like Mail does with the number of unread messages)and notification options are customizable by each iPhone user. All around, it’s a good compromise between Apple’s one-app stance and keeping you connected to what you want all the time.

Voice Recorder

Voice Recorder is, well, a voice recorder. This app is pretty simple, but it offers pretty good recording quality, the ability to add descriptions about recordings, basic editing/trimming of recordings, sharing by email, and the ability to sync them to your iTunes library (where they are also automatically added to a Voice Recordings playlist). It’s a great feature for quick notes to yourself, recording a podcast on the run (though you’ll need some post processing to get the recording online), and even recording lectures or presentations.

NOTE

Voice Recorder is available on the iPod Touch, but it requires an external mic or appropriate iPhone or iPod headset.

Buying and Renting Anything in the iTunes Store

The entire iTunes Store is now accessible on your iPhone or iPod Touch. You can preview, buy, and rent movies or buy TV shows and audio books. This is great feature if you’re stuck on in airport or elsewhere with time to kill because you’re no longer bound to what you’ve already synced (though you are still bound by the speed of your Internet connection a bit). Not only is the entire iTunes Store available but via the new Store option in the Settings application, you can also manage your iTunes account directly from your iPhone or iPod Touch.